1. Field
Various exemplary embodiments of the present invention relate to a high voltage switch circuit which is used to transfer a high voltage.
2. Description of the Related Art
Nonvolatile memories retain data even though their power supply is interrupted. Among such nonvolatile memories, a floating gate type nonvolatile memory, which is currently prevalent, utilizes a floating gate that is disposed over and insulated from the channel region of a substrate. In particular, the nonvolatile memory utilizes the threshold voltage of a memory cell that depends on the amount of charge retained in the conductive band of the floating gate.
A nonvolatile memory includes a memory cell array for storing data. The memory cell array has a plurality of memory blocks. Each memory block has a plurality of pages. Each page has a plurality of memory cells. The respective memory cells are classified into on-cells and off-cells according to their threshold voltage distributions. On-cells are erased cells, and off-cells are programmed cells. The nonvolatile memory performs an erase operation by the unit of a memory block, and performs a program or read operation by the unit of a page.
The nonvolatile memory may store 1 or more-bits of data in a single memory cell. A memory cell that stores 1-bit data is referred to as a single level cell (SLC), and a memory cell that stores 2 or more bits of data is referred to as a multi-level cell (MLC). The single level cell has an erased state and a programmed state that are determined by its threshold voltage. The multi-level cell has an erased state and a plurality of programmed states that are determined by its threshold voltage.
In a nonvolatile memory, which has multi-level cells, it is important to narrow the widths of threshold voltage distributions of programmed states, and thereby secure margin between the respective programmed states. Generally, 2-bit data or 3-bit data is stored in the multi-level memory cells of the nonvolatile memory. In this regard, by setting the voltage of an erased state and partial threshold voltages of a plurality of programmed states, to a negative level, the performance and the reliability of the nonvolatile memory having the multi-level cells may be improved.
Meanwhile, the plurality of memory cells included in a block are connected with a plurality of global word lines through a plurality of switches. When the corresponding block is selected, the voltages of the plurality of global word lines are transferred to a plurality of local lines, which are connected with the plurality of memory cells, through a plurality of high voltage switches, and, when the corresponding block is not selected, the voltages of the plurality of global word lines are interrupted by the plurality of high voltage switches. Accordingly, there is demand for high voltage switches that reliably transfer high voltages of global word lines to local lines when a corresponding block is selected, and reliably interrupt the high voltages of global word lines when a corresponding block is not selected, and a control technology thereof.